This invention relates to an assembly wedge for two adjoining voussoirs in a tunnel shield for a railroad or the like.
Commonly assigned U.S. Pat. No. 4,318,637 describes a device for the assembly of tunnel shield voussoirs comprised of cylinder segments whose facing sides bear a certain curvature. This device includes two pairs of wedges each arranged at an end of the voussoirs in corresponding housings, and radially connected by bolts which bring the wedges together while tightening them to contact the adjoining sides of the voussoirs. These wedges or pins are satisfactory, but it is sometimes difficult to obtain the exact angle desired between the two voussoirs, i.e. the angle between the planes tangent to their curved external or extrados surfaces at their interface. To do this the two wedges must be separately and simultaneously positioned in the radial direction at the desired location, taking into account the angle sought between the voussoirs. Moreover, the strain sustained by the voussoirs is concentrated on the wedges, which can lead to their plasticization or deformation due to crushing.
French Pat. No. 73/29,114 discloses a voussoir assembly system comprising a series of prismatic wedges selected in a range of dihedral angles adapted to the desired angle, following which the voussoirs are assembled with the wedges superimposed between them and fastened by bolts and nuts. This assembly device requires the use of a wide assortment of wedges.